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<head><meta charset="utf-8"><title>Unstable fingerprints · t-compiler · Zulip Chat Archive</title></head>
<h2>Stream: <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/index.html">t-compiler</a></h2>
<h3>Topic: <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/Unstable.20fingerprints.html">Unstable fingerprints</a></h3>

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<a name="231367766"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/Unstable%20fingerprints/near/231367766" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> simulacrum <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/Unstable.20fingerprints.html#231367766">(Mar 22 2021 at 19:14)</a>:</h4>
<p>Hey <span class="user-mention" data-user-id="125294">@Aaron Hill</span> - syn is failing on rustc perf with unstable fingerprints, particularly evaluate obligation - IIRC you had mentioned that it was painful to track down a minimal reproducer, but this is hopefully deterministic now?</p>



<a name="231367856"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/Unstable%20fingerprints/near/231367856" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> simulacrum <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/Unstable.20fingerprints.html#231367856">(Mar 22 2021 at 19:14)</a>:</h4>
<p>(also wondering if we should disable the benchmark or if there's a fix in the pipeline)</p>



<a name="231367871"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/Unstable%20fingerprints/near/231367871" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> simulacrum <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/Unstable.20fingerprints.html#231367871">(Mar 22 2021 at 19:14)</a>:</h4>
<p><a href="https://perf.rust-lang.org/status.html">https://perf.rust-lang.org/status.html</a></p>



<a name="231368101"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/Unstable%20fingerprints/near/231368101" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> lqd <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/Unstable.20fingerprints.html#231368101">(Mar 22 2021 at 19:16)</a>:</h4>
<p>should be fixed by <a href="https://github.com/rust-lang/rust/pull/83220">https://github.com/rust-lang/rust/pull/83220</a></p>



<a name="231368346"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/Unstable%20fingerprints/near/231368346" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> lqd <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/Unstable.20fingerprints.html#231368346">(Mar 22 2021 at 19:17)</a>:</h4>
<p>(hopefully, if that's indeed <a href="https://github.com/rust-lang/rust/issues/80691">#80691</a>)</p>



<a name="231369118"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/Unstable%20fingerprints/near/231369118" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> lqd <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/Unstable.20fingerprints.html#231369118">(Mar 22 2021 at 19:21)</a>:</h4>
<p>I wasn't able to reproduce the syn failure locally for this query, but I managed to do so and reduce some of the others, like chalk in <a href="https://github.com/rust-lang/rust/issues/83115">#83115</a>, or <a href="https://github.com/rust-lang/rust/issues/83226">#83226</a></p>



<a name="231369418"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/Unstable%20fingerprints/near/231369418" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> simulacrum <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/Unstable.20fingerprints.html#231369418">(Mar 22 2021 at 19:23)</a>:</h4>
<p>Interesting that you can't reproduce - I wonder if that points to something special about the perf environment (e.g., we're sharing build cache in some way).</p>



<a name="231370129"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/Unstable%20fingerprints/near/231370129" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> lqd <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/Unstable.20fingerprints.html#231370129">(Mar 22 2021 at 19:26)</a>:</h4>
<p>yeah I didn't investigate much on rustc-perf, just tried to build in the syn benchmark folder directly (and then focused on the other cases for a couple days <span aria-label="sweat smile" class="emoji emoji-1f605" role="img" title="sweat smile">:sweat_smile:</span> since I could reproduce)</p>



<a name="231370353"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/Unstable%20fingerprints/near/231370353" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> lqd <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/Unstable.20fingerprints.html#231370353">(Mar 22 2021 at 19:27)</a>:</h4>
<p>perf was run on this PR and syn worked</p>



<a name="231371274"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/Unstable%20fingerprints/near/231371274" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> simulacrum <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/Unstable.20fingerprints.html#231371274">(Mar 22 2021 at 19:32)</a>:</h4>
<p>yeah, it worked before and after though - not quite clear :)</p>



<a name="231371547"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/Unstable%20fingerprints/near/231371547" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> lqd <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/Unstable.20fingerprints.html#231371547">(Mar 22 2021 at 19:34)</a>:</h4>
<p>I'll try to reproduce again</p>



<a name="231371829"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/Unstable%20fingerprints/near/231371829" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> simulacrum <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/Unstable.20fingerprints.html#231371829">(Mar 22 2021 at 19:36)</a>:</h4>
<p>I don't think it's super important if we already have a possible fix in mind</p>



<a name="231372141"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/Unstable%20fingerprints/near/231372141" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> lqd <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/Unstable.20fingerprints.html#231372141">(Mar 22 2021 at 19:38)</a>:</h4>
<p>it would be good to have some kind of test for the PR (and maybe we could use e.g. the chalk minimization I did, but it's not super small per se) but otherwise it seems ready to review</p>



<a name="231372203"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/Unstable%20fingerprints/near/231372203" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> lqd <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/Unstable.20fingerprints.html#231372203">(Mar 22 2021 at 19:38)</a>:</h4>
<p><span class="user-mention silent" data-user-id="116122">simulacrum</span> <a href="#narrow/stream/131828-t-compiler/topic/Unstable.20fingerprints/near/231371829">said</a>:</p>
<blockquote>
<p>I don't think it's super important if we already have a possible fix in mind</p>
</blockquote>
<p>yeah, but at least we'd be able to test the try build artifacts then</p>



<a name="231374447"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/Unstable%20fingerprints/near/231374447" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> lqd <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/Unstable.20fingerprints.html#231374447">(Mar 22 2021 at 19:53)</a>:</h4>
<p>(no luck on rustc-perf, but the try build does fix chalk for me)</p>



<hr><p>Last updated: Aug 07 2021 at 22:04 UTC</p>
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